Abstract: A self-drilling anchor installable in a wall by means of a screwdriver, the anchor being adapted to receive a threaded fastener serving to hold a fixture against the wall. The anchor includes an externally-threaded shank section having a head engageable by the screwdriver and a longitudinal bore threadably to receive the fastener. Integral with the shank section and extending axially therefrom is a drill section having at least one cutting member and guide means therefor, whereby as the anchor is turned in to the wall by a screwdriver, the cutting member then bores a round hole therein whose bank is engaged by the guide means to ensure circularity of the hole. And as the anchor continues to turn, the shank section enters and taps the hole until its head engages the outer surface of the wall to complete the anchor installation.

Abstract: A bolt includes a movable pin in the center thereof. This pin can freely move up and down in the bolt. If the pin protrudes out of bolt a predetermined distance after the bolt is screwed into a blind bolt hole, then an inspector knows that the bolt is fully engaged. If, on the other hand, the bolt is not fully engaged, the pin will not protrude the predetermined distance out of the bolt. A second embodiment of the similar invention is a stud having an indicator pin. In third and fourth embodiments, the bolts and studs have indicator pins including grease zerks. These grease zerks allow the holes to be filled with grease to prevent damage to the hole due to corrosion.

Abstract: An dual tapered orthopedic fixation screw is used to anchor ligament grafts inside a bore in a bone mass. The fixation screw includes a root portion having a front section, a cylindrical center section and a back section. A screw thread is formed over substantially the entire root portion to increase purchase. A taper is formed on the back of the root portion to increase compression of the fixation screw against the ligament graft. The screw further includes a rounded portion that is formed between the taper and the back end of the root to prevent the screw from fraying or cutting the ligament.

Abstract: A self-drilling anchor installable in a wall by means of a screwdriver, the anchor being adapted to receive a fastener serving to hold a fixture adjacent the wall. The anchor includes an externally-threaded shank section having a head engageable by the screwdriver and a longitudinal bore to receive the fastener. Integral with the shank section and extending axially therefrom is a core drill section whose bit includes at least one cutting blade and whose outer cylindrical surface acts as guide means whereby as the anchor is turned in to the wall by a screwdriver, the cutting blade then bores a round hole therein whose bank is engaged by the cylindrical surface to ensure circularity of the drilled hole. And as the anchor continues to turn, the shank section enters and taps the drilled hole until its head engages the outer surface of the wall to complete the anchor installation.

Abstract: A folding lock knife includes a handle member having a handle cavity arranged to receive a lock blade therewithin, wherein the lock blade includes a first end, the first end including an arcuate array of ratchet teeth arranged for selective cooperation with a lock lever having a lock lever foot received between a plurality of such teeth to selectively secure the blade member in a preselected orientation relative to handle portion of the knife assembly.

Abstract: A wall anchor for insertion in wall board and having a cylindrical body with an outer thread and an axial through passage extending from a flanged proximal end to a saw-tipped distal end. The cylindrical body comprises a proximal extension and a distal extension of approximately the same length equal to the width of wall board. The flange at the proximal end may be provided with locking tabs and the saw-tipped end may be provided with mashing teeth on a circumference of revolution smaller than that of the sawing teeth.

Abstract: The screw (1) comprises an end formed by a dog point (2) having a plane transverse surface (3) and a cylindrical lateral surface (4) connected to the plane surface (3) by a rounded annular radius (5), it also comprises a threaded part (6) contiguous with the dog point (2) in which a self-tapping zone (8) is made which terminates at the base of the dog point (2), a smooth cylindrical part (9) being moreover arranged between its threaded part (6) and its head (11). The smooth part (9) is connected to the head (11) by an inclined plane zone (12). The rounded dog point (2) makes it possible to hold back without harming any mucosa or aponeurosis situated behind a bone through which the screw passes. The smooth parts (9 and 12) avoid damage to the skin of the patient. This screw is intended to be positioned very precisely and to remain anchored in the patient for the whole time necessary for the planned investigations, which avoids repeated piercing of the cranium or of any bone at each examination.

Abstract: A liquid level sensor has a liquid sensing element carried on the end of a curved probe which is inserted into a liquid-holding chamber. The probe can be rotated to properly locate the sensor within the chamber. A threaded nut locks the curved probe in position to maintain the sensor in the proper position.

Abstract: An elbow fitting of selected member configurations and comprised of two members separately machined utilizing bar stock exterior form and one of which is cross drilled for assembly with the other and preferably adapted to rotatably receive a swivel spout sealed and secured therein, using less material, requiring less machining, and cost effective.

Abstract: A self-drilling anchor installable in a wall by means of a screwdriver, the anchor being adapted to receive a threaded fastener serving to hold a fixture against the wall. The anchor includes an externally-threaded shank section having a head engageable by the screwdriver and a longitudinal bore threadably to receive the fastener. Integral with the shank section and extending axially therefrom is a drill section having at least one cutting member and guide means therefor, whereby as the anchor is turned in to the wall by a screwdriver, the cutting member then bores a round hole therein whose bank is engaged by the guide means to ensure circularity of the hole. And as the anchor continues to turn, the shank section enters and taps the hole until its head engages the outer surface of the wall to complete the anchor installation.

Abstract: A screw fastener and a tool for driving the screw fastener is disclosed. The screw fastener has a polygonal driving socket in its head, the driving socket having a substantially square first section and a second section including a rectangular slot radiating outwardly from the center of each side wall of the first section. The depth of the first and second sections are the same. Further, the screw fastener may be provided with internal ducts for conveying lubricant into a workpiece hole in which the fastener is being turned. A driving tool having a square shank for turning the screw fastener is also disclosed. One end of the tool's shank has a driving section comprising a rectangular fin extending longitudinally along and radiating outwardly from the center of each side wall of the shank. The shape of the driving section is complementary in shape to, and dimensioned to be snugly received in, the driving socket.

Abstract: A preheat device for preheating an internal combustion aircraft engine having an air intake pipe connected to a cylinder head by threaded mounting bolts is configured as a replacement bolt with a zinc - plated body having a bolt head and threaded shank. The body is made of steel heat treated to grade 8 hardness and tempered at apprximately 1,050 degrees F. and had an axial bore open at the head and extending toward and into the shank. An electric heating element surrounded by a stainless steel sheath is positioned in the bore. The shank has a thread with a flat root to provide a wall thickness approximately 0.060 inch. Each cylinder of the engine is provided with a preheat device in place of a mounting bolt and the preheat devices are connected to each other by a wiring harness connectable to an external power source. When energized the heating element of each preheat device generates heat that in transferred through the screw threads to the cylinder head of the engine cylinder.

Abstract: A cannulated bone screw is illustrated that retains a knotted suture and which is anchored to bone. The cannulated bone screw comprises a biocompatible body having a proximal end and a distal end, and the body includes exterior screw threads for inserting and retaining the body into the bone. The body is cylindrical and has a passageway that extends axially therethrough. The passageway includes a central portion, a distal portion and a proximal portion. The central portion has a diameter less then the distal portion and is sized to receive a suture thread therethrough. The distal portion is sized to receive a suture thread knot. The suture thread knot received within the distal portion is retained by the central portion, which is sufficiently small to prevent the knot from being drawn therethrough. The proximal portion includes a hexagonal cavity for cooperating with an external drive tool for rotating the body and thereby driving the body into the bone.

Abstract: A fluid cooled thermal skin is bolted to a sufficient back structure. In-line coolant flow paths are arranged to pass the cooling fluid through the bolt head. The in-line paths are recessed adjacent the bolt head to mate with flow openings in the head. In one embodiment the paths through the bolt head are parallel paths, requiring alignment of the bolt head. In another embodiment alignment of the bolt head is not required.

Abstract: A shoulder screw having a centrally positioned borehole concentric with respect to the longitudinal axis of the screw and a cylindrical center-tapped bolt receiver loosley positioned within the centrally positioned borehole of the shoulder screw and coupled thereto by a roll pin positioned perpendicularly with respect to the axis of said shoulder screw, the diameter of the bolt receiver being less than the diameter of the borehole, for enabling the bolt receiver to translate in a direction transverse to the axis of the shoulder screw.

Abstract: A removable threaded fastener is provided which comprises a head component; an externally threaded shank component; and a resilient linking means connecting the head and shank components. The fastener has a longitudinal opening adapted to receive a tool for the application of torque in a driving engagement with the shank component without an integral torque transfer means. Also provided is a method for removably fastening a work piece using the removable threaded fastener by inserting the fastener through a threaded aperture in the work piece; inserting the tool into the longitudinal opening; applying torque to the shank component sufficient to cause axial displacement of the shank component against the resilient biasing of the linking means to maintain the head and shank components in axial tension; and removing the tool.

Abstract: A failure indicating device wherein a fluid is encased within a bore in a fastener. In another embodiment of the invention, the fluid is encased within a thin walled capsule which in turn is encapsulated within a bore in the fastener. Upon failure of the fastener, the encased fluid will leak out into the external surface and its detection will indicate that the fastener has failed. The stress which causes the fastener to fail will also assist the fluid to leak out onto its external surface. To facilitate the leakage of the fluid, one or more shallow and narrow groove(s) may be machined onto the external surface of the fastener so that the leaked fluid will travel along this groove(s) to the preferred external end of the fastener. This is desirable in cases where only one side of the joint is accessible.

Abstract: This invention deals with a device which is useful for the securing of roof structures, especially laminar type roof structures wherein an integral, obstensibly waterproof, covering is used as part of the laminar structure. It also deals with a unique method of detecting leaks in roofing structures which allows the location of such leaks with a certain preciseness by using the fastening devices of this invention as points of reference.

Abstract: An apparatus and method for heating hollow bolts (20) mounted in aligned openings (18) of a pair of members (10,12) to be connected together. A conduit (42) supported by a cylindrical body (40) from the end (29) of the bolt (20) is inserted within the bore (34) of the bolt (20). A fired stream of heated fluid from a gas torch (90) flows through the conduit (42) thereby to heat the bolt (20) for providing sufficient elongation for predetermined tightening or loosening of the associated nut (30). One embodiment (FIG. 1) utilizes a hollow bolt having a blind end central bore (34). Another embodiment (FIG. 3) utilizes a hollow bolt (26A) having a central bore (34A) extending through the entire length of the bolt (26A).

Abstract: The present invention provides a heavy duty seal for hasps and latches in combination with a light duty tamper-indicating seal, which extends through the heavy duty seal for indicating tampering or breaking of the heavy duty seal. A sheathed bundle of optical fibers extends through aligned bores in parts of a heavy duty bolt type seal. End portions of the bundle are locked in a locking block and terminal ends of the fibers are exposed in surfaces of the block for observation and indications of light transmittal.

Abstract: An apparatus for repairing in vivo torn cartilaginous or other bodily tissue, particularly torn meniscus tissue during arthroscopic surgery, employs a repair tack of biodegradable material chosen to have a degradation time in excess of the required healing time for the tissue. The repair tack has a shaft portion with a longitudinal bore and a grip portion adapted for releasable engagement by a hollow applicator. In one embodiment the grip portion of the tack is a cross bar, at the proximal end of the shaft, which fits into an open-sided slot at the forward end of the applicator.

Abstract: An apparatus for repairing in vivo torn cartilaginous or other bodily tissue, particularly torn meniscus tissue during arthroscopic surgery, employs a repair tack of biodegradable material chosen to have a degradation time in excess of the required healing time for the tissue. The repair tack has a shaft portion with a longitudinal bore and a grip portion adapted for releasable engagement by a hollow applicator. In one embodiment the grip portion of the tack is a cross bar, at the proximal end of the shaft, which fits into an open-sided slot at the forward end of the applicator.

Abstract: A pivoting adjustment screw for mounting the bolt of a latch to provide vibrational damping along with increasing preload as the contact point of the adjustment screw to the mating structure shifts in a shock or vibrational environment. The adjustment screw includes a pivoting portion which permits the screw to pivot which allows a rotating rather than a scraping or abrading movement in response to the relative movement between the elements being connected.

Abstract: An anchor and stress plate assembly adapted to secure an insulation layer to the deck of a roof without penetrating the lower surface of the deck which is formed either of relatively soft or hard decking material. The anchor is provided with a flanged head and a shank whose leading section takes the form of an auger screw having a root which tapers toward the tip and a threading about the root whose crests are of approximately uniform diameter. When the anchor is turned into soft decking material, the tapered root of the auger screw then acts to pack this material into a dense mass in the region surrounding the screw to enhance the holding power of the anchor. In hard decking material, a hole must first be drilled therein to receive the auger screw whose root when the anchor is turned in fits within the hole and whose crests then cut a thread in the hole wall to securely retain the anchor.

Abstract: A lock nut assembly comprises a sleeve bolt (1), a clamp bolt (6) and a locking bolt (7). The sleeve bolt (1) has a hollow shank with an internally threaded portion (5) at one end and a head (3) having an axial bore (2) extending through it at the other end, at which it is internally threaded (4). The clamp bolt (6) also has a hollow shank with an externally threaded central portion (9) and an internally threaded portion (10) at one end (10) and a head (8) at its opposite end. The locking bolt (7) has an externally threaded portion at one end (12) and a head (11) at its opposite end. The central portion (9) of the clamp bolt (6) and the internally threaded portion (5) of the sleeve bolt (1) are dimensioned for co-operation with threads of one hand, and the second portion (10) of the clamp bolt (6) and the externally threaded portion (12) of the locking bolt (7) are dimensioned for co-operation with threads of opposite hand.

Abstract: A junction bolt for joining members by use of clamping nuts engaged with the junction bolt is provided with an axial inner hollow hole in which a piston member is located so as to define a space between the outer peripheral surface of the piston member and the inner wall of the junction bolt. The space is divided by a sealing member into a pressurizing space into which a pressurized fluid is introduced and a temperature adjusting space into which a heat medium is introduced. In the bolt clamping force adjusting method, the temperature of the junction bolt is first adjusted to a predetermined temperature and an extending amount of the junction bolt to be caused when an aimed clamping force is applied at this predetermined temperature.

Abstract: A series of drywall screws are nested together and individually seated with a special driving tool after separation from one another. Each screw is hollow and has interior and exterior screw threads. One end of the screw has a hollow flat head and the body tapers downwardly to a bottom portion having a diameter less than half the diameter of the first end. A drill bit having an eccentric point drills a bore having a diameter greater than the diameter of the drill bit so that the bore operatively receives the screw.

Abstract: The invention relates to an adjustable securing means, preferably of metal, for joining two components (1,2) together. It comprises a holding element (3) which can be incorporated into an adapted hole in the component (1) at the side of the component (1) facing the component (2). The holding element (3) is provided with an internal thread and comprises a collar (8). The securing means further comprises a force-transmitting element (7) which is provided at least partially with an external thread and is screwable into the holding element (3) and has a through hole (8) with a stop (a) or the like at one end, the hole (8) being otherwise completely or partially formed with polygonal cross-section. The holding element (3) consists of a relatively narrow sleeve-like ring (6). The internally threaded holding element (3) comprises a lip projecting radially from its peripheral face and axially spaced from the collar and a lug (16) which lies in the plane of the collar (8) opposite the lip (12 ) and has a hole (18).

Abstract: A method of forming a lightweight threaded fastener element of bimaterial construction to high tolerance requirements, the element formed by the steps of shaping a metal shell to a preliminary configuration blank by extrusion, filling the extruded shell with a less dense material such as a curable epoxy-graphite material or an aluminum-lithium alloy, further shaping the filled blank by forging both the core material and shell to an intermediate configuration which is finished by warm rolling to form a strong lightweight fastener element configured with the metal shell thereof which may be engageable with a cooperating metal fastener assembly member.

Abstract: Fastener 36 threaded to stud 32 carries disk 46 which retains panels 16. Cooling air 14 passes through an axial opening 34 cooling the center of the disk by impingement cooling. Uniformly spaced involute shaped openings 48 carry cooling air to cool the balance of the disk.

Abstract: The governor includes a torque-control capsule actuated by a governor member that adjusts in accordance with rpm and disposed in a force-transmitting member subject to the force of a governor spring, by means of which torque-control capsule both the onset and control stroke (b) of torque control are adjustable or settable in an infinitely graduated manner without affecting one another. The torque-control capsule has a stop bolt inserted in a stepped longitudinal bore of a stop housing, a torque-control spring and an adjusting screw, which forms an abutment for the torque-control spring. The adjusting screw is adjustable in an infinitely graduated manner and is secured in a positionally fixed manner inside the stop housing in the vicinity of an internal thread.

Abstract: A freeze safe valve has a valve body, a valve gate, a washer, a fastener having an interior channel, and a plug placed in the channel of the fastener. With fluid pressure in the normal downstream direction, the plug will be held in place, and the valve will function as a standard valve. However, when net pressure exists in the upstream direction at a certain predetermined level due to, for example, the formation of ice on the downstream side of the valve, the plug will become dislodged so that fluid may flow back to the upstream side. This will alleviate the pressure on the downstream side and ideally will preclude breakage of the downstream pipe or the valve itself.

Abstract: A fastener for anchoring in a bore in a bone has a screw having a substantially cylindrical outer surface formed with a helical screwthread. This screw has at its screwthread a thread diameter and between the turns of the thread at the surface a root diameter smaller than the thread diameter. A synthetic-resin anchor sleeve of a resilient fitted in the bore is of an outside diameter corresponding generally to the diameter of the bore and has an outer end formed with an outwardly open polygonal-section recess, an inner end formed with an inwardly open and transversely throughgoing slot, an outer end portion of an inside diameter greater than the root diameter but smaller than the thread diameter, an inner end portion of an inside diameter smaller than the root diameter, and an external helicoidal screwthread extending about two-thirds of the length of the sleeve from its inner end toward its outer end.

Abstract: A swivel connector for connecting a first and second line for towing of one line by the other wherein there is provided an upper limit on loading that may be imposed between the lines as a safeguard to damage to one of the lines. The swivel connector includes first and second swivel heads connected by a load pin. The load pin is fixed to fracture at an approximate predetermined loading between the first and second swivel heads which loading is beneath that which would otherwise cause danger or damage to one of the lines. Upon fracture of the pin, it is readily replaced so that the swivel head can be used again.

Abstract: A device for adjustably fastening a door or window frame or the like to a fixed element, including a screw-like device having threads which engage the fixed element and a threaded sleeve member, displaceably arranged on the screw-like device, which engages the frame.

Abstract: A threaded fastener for installation in threaded engagement with an initially unthreaded apertured workpiece and which after installation can be removed in the manner of a screw or bolt, has a shank and an enlarged head. At least part of the shank intermediate between its ends has an external screw thread having a sharp crest, and can be radially expanded to cause the thread to embed in the workpiece. A bore extends through the head and the entire shank or at least the threaded part of the shank for receiving means for expanding the shank. An end portion of the shank remote from the head may be unthreaded to avoid splitting of the shank during expansion.The method of installing the fastener involves pulling a tapered mandrel along the bore to expand the shank. The mandrel may have a key-forming head of non-circular cross-section whereby the bore of the fastener can be adopted to receive a key of non-circular cross-section for turning the fastener in the workpiece.

Abstract: A fastening assembly for use in attaching articles to soft materials such as gypsum based and light weight concrete roofing. The assembly includes an anchoring element which has a high thread and an axial bore in one end. The thread has an included angle of less than 45.degree. and terminates in a sharp edge at the free end of the anchoring element. A headed screw is driven into the bore and becomes fixed to the anchoring element. A flange is integrally molded and frangibly connected to the bored end of the anchoring element, and becomes a washer upon breaking away therefrom.

Abstract: A threaded insert for drywall having an externally threaded portion and an unthreaded drilling portion of generally equal lengths. The insert is adapted to be installed in a single step with the use of a hand powered screwdriver. A low profile flange at the upper end spaced a distance from the threads allows the insert to be installed flush with the surface of the drywall. Two embodiments are disclosed, one of molded zinc and the other of plastic material. Both embodiments include a drilling portion which can be deflected laterally upon the insertion of a screw therethrough, allowing the use of a single moderate length screw for attaching articles of various thicknesses. The insert eliminates the need to pre-drill a hole with a separate tool.

Abstract: A safety closure of an aerosol can comprises an externally screw threaded sleeve having a slit extending along one side thereof and an inwardly extending flange at its lower end. The flange is engageable below an upper peripheral rim of the aerosol can after the sleeve has been temporarily flexed apart along its slit to enable the flange to pass over the rim. An internally screw threaded safety cap threadedly engages over the threaded sleeve and prevents the sleeve from flexing apart along the slit so locking the flange under the rim. The safety cap can only be unscrewed from the sleeve if the cap is additionally pressed firmly downwards. Advantageously the safety cap is of a type used as a childproof closure for medicines.

Abstract: The invention relates to an overload protection device for a machine tool, in which a carriage carried on the machine bed is displaceable, between the tailstock and the headstock by a lead screw [driven] by a drive motor and a feed gearing, and in which the lead screw nut is joined to the carriage by at least one joining bolt. To permit a very quick restoration of the machine to service after a collision between the carriage and a component present in its path of movement, while the predetermined dimensional relationship is restored without additional readjustment, the overload protection device is constructed such that the joining bolt has a break-away section in the area of the junction between the carriage and the lead screw nut.

Abstract: An elongate pin extends in an axial bore in a threaded fastener, at least one end portion of the pin protruding from the bore. An abutment is provided on said one end portion, while when the fastener is in an unstressed condition may rotate about the longitudinal axis thereof. Conversely, when the fastener is subjected to a predetermined tension, rotation of the abutment is prevented by engagement with an end face of the fastener.

Abstract: A unique connector and insertion tool are disclosed. The connector is hollow with screw-type threads on its outer surface, an enlarged head at one end and a non-sharp configuration at the other end. The insertion tool has a non-sharp elongated shaft or piercer attached to a handle; the end of the piercer is adapted to allow piercing and passage through the materials being secured together. The connector slides over the piercing shaft, is held in secure non-rotating relation thereto, and is configured to penetrate the materials and be screwed into place by the insertion tool. The entire piercing and connection operation may be conducted in a twisting motion with just one hand.

Abstract: The present specification provides a caliper for use in a disc brake. The caliper has at least two body sections which are clamped together by one or more bolts, each bolt having a bore extending axially therethrough, the bores acting as pin guides for the pins secured to the torque taking member, in the complete brake. Thus only a pair of holes are required to be formed in the caliper body sections, improving the strength and rigidity of the caliper and keeping manufacturing costs to a minimum.

Abstract: The present invention relates to a threaded member incorporating structural features which prevents more than a required amount of torque or rotational force to be applied thereto. More particularly, the shaft of the threaded member is hollow and slotted so that it buckles or collapses inwardly when the member bottoms out.

Abstract: A metal fastener having a well-defined yield point and improved elongation beyond the yield point and a tensile strength (force) at least as large as the specified minimum for the grade, size, and threads of said metal fastener, the metal fastener of nominal diameter D, which metal fastener comprises in combination: an externally threaded component having threads of nominal diameter D; a circular, cylindrical shank component having a diameter D.sub.

Abstract: A hand held tool for installing a threaded fastener in which the tool is adapted for use solely as a drill bit, solely as a screwdriver, and as a combination thereof, wherein the threaded fastener has a central bore extending therethrough. Extension of the drill bit beyond the end of the screwdriver blade may be selectively controlled, and the drill bit may be maintained in its entirety within the shaft of the screwdriver when not in use to thereby preserve the sharpness of the drill bit. A unique locking collar is also provided.

Abstract: A structure serving for use in the tie-down of cargo on the bed of a truck characterized by a body member, partly threaded both externally and internally, which has been inserted into a hole drilled through the truck bed, and a further assembly including both a positioning or plug member and a nut disposed beneath the truck bed and threadedly secured to external threads on the stem of the body member. The head of the body member and the positioning member each have complementary outwardly flaring surfaces, so that, when drawn together by wrench means, the top surface of the body member is in a generally flush relationship with the surface of the truck bed adjacent the hole. The internal threads of the body member typically receive an eyehook, which, in turn, receives a rope or the like for positioning the cargo on the bed of the truck.

Abstract: A tacking rivet has a shaft and a head with a longitudinal bore through the haft and through the head. The head forms a rim extending radially outwardly and the rim or head has a divider which divides the head and/or rim into at least two portions. The divider may, for example, be a slot or recess or indentation.

Abstract: A shock and vibration-proof fastener of general application and particularly suitable to hold dual wheels demountably assembled to a cargo vehicle hub. The fastener is designed to isolate the threads thereof from radial and torsion stresses utilizing a split collet encircling the shank of the fastener with its periphery converging toward the collet ends at angles of the order of 4 to 1 relative to the collet axis and having a nesting interference fit with a similarly tapered bore through the parts or wheels to be clamped together. The fastener shank has a threaded well in one end mateable with a cap screw having a self-aligning conical surface on the underside of its head engaging the rim edge of a loose fitting washer. The self-aligning surfaces are preferably provided with a ring of teeth and notches interengaging along helical surfaces having a pitch substantially greater than that of the fastener threads.